The present invention relates to a vertical vibration-damping apparatus which is set mainly on floors of a building for protecting vibration sensitive office automation equipment or the like from vertical vibrations based on a vertical type earthquake, various construction works, road traffic, etc.
With the recent spread of office automation equipment, vibration-damping constructions of buildings and vibration-damping floors have been developed increasingly so as to protect the vibration sensitive equipment from being damaged by earthquake or the like. Some such constructions and floors have been realized (refer to, for example, U.S. patent Ser. No. 99,326 corresponding to Japanese Published Unexamined Patent Application Nos. 62-86265 and 62-86266).
However, all the conventional vibration-damping apparatuses are constructed to be effective against horizontal vibrations. There is no developed damping apparatus for the vertical vibrations.
Until now, vibration-damping means has been proposed to protect the office automation equipment from being damaged by the vertical vibrations. It is a problem maintaining this office automation equipment.
It may be considered as a primary construction theory of the vertical vibration-damping apparatus to provide coil springs vertically under the vibration-damping floors, on which the office automation equipment is provided, so that the former supports elastically the latter. However, such a construction requires that the length of each coil spring is the sum of a basic spring length and a vertical vibration stroke length for insuring to damp the vibration by this stroke length. If the vibration-damping apparatus employs such long springs vertically, the position of the vibration-damping floor may be high, and the high position floor is not comfortable to use. An index to the solution of this problem is apt to limit the stroke of the vertical vibrations, and thereby the vibration-damping is not effective to the long period vibrations.
In addition, if the coil springs are used vertically, locking may occur. This is another problem.